It has conventionally been known that carbon dioxide (carbonic acid anhydride: CO2) has both properties of being not only soluble in water (water-soluble) but also soluble in fat (fat-soluble) and, therefore, by only contacting the skin and mucous membrane of the living-body being like mixed with water and fat, carbon dioxide penetrates under a subcutaneous layer and expands blood vessels around the parts of penetrated carbon dioxide, and it works to improve the blood circulation. Owing to this action of accelerating the blood circulation, it displays various physiological effects such as dropping of blood, pressure, improving of metabolism or accelerating to remove pain substance or waste product. Further, it has also anti-inflammation and anti-bacterial. Therefore, carbon dioxide has recently been given attentions also from viewpoints of improving health or beauty other than the purpose of medical cares.
Carbon dioxide in the tissue of the living-body works to release oxygen carried in combination with hemoglobin in a red blood cell. Around parts at a high density of carbon dioxide, the red blood cell releases more oxygen. Thus, supply of oxygen to cells by the red blood cell is mainly controlled by carbon dioxide. In short, being without carbon dioxide, hemoglobin remains as combined with oxygen, and the cell becomes unable to receive oxygen. As is seen, carbon dioxide seems to have been a waste product resulted from action of the cell, however, it plays in fact very important roles in the living-body.
Further, in recent times, oxygen of high density has also widely been known as effective in activity of metabolism, fatigue recovery or stability of blood pressure.
As a prior art for causing carbon dioxide to be absorbed into limited parts of the human living body, in particular the head (frontal region, parietal region, occipital region, temporal region, face and neck), there has been disclosed up to now, for example, a cosmetic instrument of causing hot water dissolved with carbon dioxide to flow down on the face and to be absorbed into the faces skin (for example, Patent Document 1). Further, there has been disclosed an instrument of attaching a closable container to specific parts of the human living body, and introducing carbon dioxide thereinto for taking a carbon dioxide bath (for example, Patent Document 2).